This invention relates to fire protection systems and more particularly to an improved sprinkler head for use in automatic sprinkler systems.
Automatic sprinkler systems are presently considered the mose dependable and effective means of fire protection. Sprinkler systems are available in basically five types. Wet pipe systems employ automatic sprinkler heads attached to piping containing water which is at all times under pressure. Upon the occurrence of a fire, individual sprinkler heads are actuated by the heat. Upon actuation, the sprinkler head nozzle is opened and water is discharged.
Dry pipe systems also employ automatic sprinkler heads which are, however, attached to piping containing air under pressure. When the sprinkler head is actuated by the heat from a fire, the air pressure is reduced and the dry pipe valve is opened by water pressure, resulting in discharge of water through the open sprinklers.
Preaction systems are also available which are actuated by heat sensitive devices or automatic fire detection systems. Such devices or systems trip a controlling valve and permit water to enter the otherwise dry sprinkler piping before the automatic sprinkler heads are actuated.
Deluge systems are available which function to deliver the most water in the least amount of time. Such systems wet down an entire fire area by admitting water to sprinklers, sprinkler heads or spray nozzles that are open at all times.
Finally, fire cycle systems are available which initially duplicate conventional preaction systems. Such fire cycle systems, however, have the additional ability to cycle on and off while controlling a fire and to shut themselves off automatically when the fire is extinguished.
Heretofore, a large variety of automatic sprinkler heads have been proposed for use in the various sprinkler systems. Typically, the sprinkler heads include a body defining a nozzle and a frame having a pair of arms which extend from the nozzle and are joined at a frusto-conical portion opposite the nozzle. Usually, some form of distributor or deflector plate is attached to the frame to prevent upward spray of liquid issuing from the nozzle and/or to insure proper distribution of the water or other fire control liquid. A thermally responsive actuator is positioned between the frusto-conical portion and a cap or valve element disposed within the nozzle. Upon attainment of a predetermined ambient temperature range, the thermally responsive element is triggered or actuated permitting release of the cap or valve element from the nozzle.
The various standards for sprinkler heads require that the head create a force which will throw the actuator clear of the head. Heretofore, this force has been created by the arms of the frame. Examples of such prior sprinklers may be found in U.S. Pat. No. 2,664,956, entitled Sprinkler Head, issued on Jan. 5, 1954, to Barz; U.S. Pat. No. 2,697,008, entitled Sprinkler Head and issued on Dec. 14, 1954, to Rowley; U.S. Pat. No. 2,724,614, entitled Spray Sprinkler and issued on Nov. 22, 1955, to Rider; and commonly owned U.S. Pat. No. 4,136,740, entitled Large Drop Sprinkler Head for High Heat Output Fires and issued on Jan. 30, 1979, to Groos et al.
The sprinkler heads disclosed in the aforementioned patents employ rigid, fusible links positioned between the valve cap element and the joined end of the arms of the frame. With these types of heads, the spring action or spring pressure created by the frame is employed to throw the link assembly free of the head upon fusion of the fusible material joining the link assembly together. For example, in the aforementioned U.S. Pat. No. 4,136,740, a sprinkler head is disclosed which includes a cap or valve element held in place by two opposing lever arms which are in turn held together by a ball bearing fusible link. The fusible link employs a eutectic solder to hold the link elements together. Upon attainment of a predetermined ambient temperature range, the solder in the link fuses. The links will then separate on the free rolling ball bearings. The lever arms, which have an offset center, are thrown clear of the head by the spring pressure of the frame. The cap or valve element is thrown out and clear of the head by water pressure.
Sprinkler heads are also available which do not employ a rigid mechanical fusible link assembly for actuation. An example of one such head is disclosed in U.S. Pat. No. 4,167,974, entitled Sprinkler and issued on Sept. 18, 1979, to Job. The sprinkler disclosed in this patent includes a glass bulb actuator positioned between the joined ends of the arms of the frame and the cap or valve element. When the predetermined temperature range is reached, the fluid contained within the glass bulb expands in volume, bursts the glass and thereby throws the glass pieces free of the sprinkler head. As a result, spring pressure created by the arms is not necessary to achieve throw out of the thermally responsive element.